So I'm doing my cosplay of Anya Stroud from Gears of War 3 and I definitely wanna put LEDs in the shoulders and stuff so I was just wondering if anyone had any advice on what kind of LEDs I should use? Obviously they'd need to be baterry powered so concealing that will also be something i'll need to work on. If anyone's done a Gears cosplay before, did you use LEDs and if you did what kind did you use??

While I've never made the cosplay, I can still offer a bit of advise as I'm doing a degree in Electronics.

I recommend getting standard SMD white LEDs (Surface mount), I just generally think they're easier to use for this sort of cosplay so that you don't have to faff about with shrink wrapping the connections and you're working with a flat surface any way.

I usually get my components from Farnell or Rapid depending on order size.

Now I'm not too familiar with the character and just did a quick google.
The way I see it, there seems to be 2 LEDs in series on each row with 5-6 sets in parallel, this totals around 10-12 per shoulder thing?

I know this is basic knowledge, but please be aware that you'll need to slot in some resistors into your circuit or else it will damage the LEDs depending on how much voltage you're supplying (I'm assuming you'll be using a 9V battery - saves buying a plastic holder for multiple AA batteries)

I did some quick calculations based on my judgements on how the circuit should look, a 120ohm resistor in series with each row should do fine. It involves more faffing about with the soldering but it will save your LEDs from getting damaged.
EDIT: A single 75ohm resistor right after the battery before all the parallel LED rows should also work.

Let me know if this makes sense or if I'm made some mistakes in my calculations. I made my own assumptions of voltage and current so your own calculations may differ. I've also literally just come back from the library after having analysed several op amp circuits and oh my days, my brain is not working any more!

For my Clayton Carmine costume and a couple of the other gears I used SMDs as CrystalNeko mentioned but if you're not great at soldering they can be frustrating and fiddly.

It really depends on your experience. PixelKitty just used Christmas lights for her Anya and she has a tutorial on how she made everything. I made a row of SMD LEDs across two circuit boards so that it could flex around the shoulder for one of the others in our Gears group (Carmine doesn't have as many big lighty bits). One thing I did do though was make a thin sheet of polymorph to use to diffuse the LED light, I think that made all the difference as you had less points of light and more of just a glow.

I think you'd want to go for ultra bright blue LEDs though. In terms of specifically what did I use, I used these. Note the size (Size: 2.0 x 1.25 x 0.6 mm) before jumping in and ordering them though as they are tiny and torturous to solder. I just soldered them onto some stripboard in parallel and they all ran off a 9v battery.

I would agree with both things previously posted. I havn't done a gears cosplay either but from the portal gun and working with mantis I know very very basic electronics.

If you do decided to work with making stuff yourself from components. Invest in a multimeter. It will save you a lot of stress. Also invest in a breadboard so you can practice the arrangements of LEDs. I really love SMDs but I do also struggle with basic electronics and find them quite difficult so if I can make something just by adding stuff that is already made I will.

For Mantis I will be using red fairy lights in the helmet because it saves a lot of stress. But for the dolls for example I need to solder two small leds from scratch.

I found a really basic book though called Switch Craft. They basically talk about electronics from a seamstress's point of view. It's extremely basic and doesn't even go into resistors but it's a really nice starting point. I actually only just got this book and enjoy the language it used. It also gave me the incentive to try working with LEDs again because after the portal gun electronics blowing up on me four times I was done 2bh

There are plenty of other more indepth and better electronics books out there - I just enjoyed the writing style and it made sense to me.

Another option is buying premade kits of electronics to solder from scratch. I would suggest getting some of these to practice your technique. But a lot of tutorials talk about buying these (I've bought this exact one:http://www.rapidonline.com/Education/Velleman-Electronic-Candle-Kit-518130 )
And changing the led colour (making sure the the value of LED changed with is the same values as original) and going from there.

Honestly give electronics a go. I don't want to put you off I just had bad experiences because I started with something way out of my depth but it is always easier to add premade kits/existing items from £land/eBay. You still get the end result with a lot less stress. But if there isn't anything suitable give it a go

ahh thank you guys so much! You've all been so helpful! I have basic electronics skills too but I was just worried, and those SMDs are teeny tiny! I'll definitely take all your advice into account! And Ria - that books looks great! I'll definitely check that out!!